This invention relates in general to disposable spray nozzles for mixing and dispensing a multi-component foam or like fluid products, and is more particularly concerned with modifications to the internal chambers of the disposable nozzle in order to produce an even spray pattern of liquid foam product being mixed and dispensed from the spray nozzle.
As is known, a disposable mixing and dispensing nozzle is typically used in connection with a dispensing gun for mixing at least two chemical products, which mixture reacts to create a third, different chemical product. The mixed chemical product is then dispensed through an exit opening in the spray nozzle. An example of the use of the spray nozzle and dispensing gun combination is disclosed in U.S. Pat. No. 3,784,110.
As is also well known from the prior art, disposable spray nozzles are primarily used in connection with the mixing and discharge of chemical components, which because of their chemically reactive nature, must be mixed immediately prior to discharge of the mixed products.
The disposable spray nozzles and dispensing gun are most commonly used in connection with the mixing of two or more foaming products which, when mixed with each other, react to create an adhesive, insulating foam, such as, a urethane foam.
Because of the nature of the urethane reaction, by far the major amount of urethane foam application is done using a two-component system. Whether the components are a resin component and pre-polymer component, as is conventional, or whether these components are differently constituted is immaterial. However, all systems have in common the requirement that the two components which are to be mixed in the spray nozzle be kept separate from each other until just before they enter the spray nozzle for mixing and immediately subsequent discharge.
It is preferable to confine the mixing activity to the interior of the nozzle to insure that the foam undergoes at lease some expansion and thorough mixing, but that the mixed, foamable product does not accumulate on the gun surface or clog the internal passages of the gun. Such accumulation could render the gun partially or completely inoperative, or at the very least require a thorough cleaning prior to the next use of the gun. The cleanup problems arise from the two component nature of the foam whose contents are (and tend to remain) fluid as long as they are not exposed to air or to each other, but which immediately thereafter react to become largely insoluble as well as of an adhesive sticky consistency.
As a result, disposable spray nozzles of the type disclosed herein and in U.S. Pat. No. 3,784,110, were adapted to be inserted into the dispensing gun to establish a fluid-tight relationship between a part of the gun and the nozzle to insure that the mixing of the chemical products occurred exclusively within the nozzle. Consequently, by arranging for the entire mixing operation to be conducted within the spray nozzle, and for the nozzle to be positively aligned or indexed and registered with the dispensing gun in fluid-tight relationship, spraying is easy, but when spraying is completed, the inexpensive nozzle assembly may be ejected or thrown away. Therefore, there are no hidden or inaccessible passages requiring cleanup by the operator. The gun may be cleaned from its exterior surfaces merely by dipping or spraying with water or solvent, but inasmuch as there are no interior passages for mixed fluids, or mixing chambers on or in the gun body, there are no chemical reaction products which would clog, dirty, or render ineffective any parts or elements of the dispensing gun.
As is known, the nozzle may be used for an extended period of time as long as the use is relatively continuous. However, if the operation is to be stopped for a number of minutes or hours, for example, the reaction clogs the nozzle, and the used nozzle assembly is merely removed and discarded, and replaced with a new one any time before the new operation is commenced.
During the use and operation of the spray nozzle and dispensing gun, the two chemical components enter the mixing chamber located at one end of the spray nozzle and, after mixing, the mixed foam product is discharged through an orifice opening at the other end of the spray nozzle.
The prior art spray nozzle as typically shown in U.S. Pat. No. 3,784,110, utilizes a single internal chamber in which the chemicals are mixed and such that the spray pattern of the mixed product is formed within that same chamber for ultimate discharge. In using nozzles of this type, the user is not always able to accurately control the spray pattern of mixed liquid foam being discharged from the dispensing gun and spray nozzle. Very often the liquid foam is discharged in an uneven pattern, thereby resulting in an uneven distribution of liquid foam product on a sprayed surface. A significant waste of the foam product, or compromise of quality resulted. Due to the high cost of the foam product, uneven discharge and distribution and the resulting waste, became problems for which no ready solution was apparent.
With the increased demand for insulated structures, particularly homes, office buildings, warehouses and refrigerated vehicles, the application of urethane and like insulating foams to building structures has become a major industry. Thus, the problem of waste of foam product has assumed great importance in view of the large quantity of such foam products currently being utilized in the building industry.
It would be very desirable to have a spray nozzle, which, because of its own configuration, will ensure that an even pattern of liquid foam is emitted from the spray nozzle during use, to eliminate excessive waste of liquid foam product, and increase the quality of foam application during the use of the dispensing gun and spray nozzle.